When letters are sent out by the direct response advertising industry and also in letters mailed as a selling/promotion tool, it is quite desirable to specifically name the recipient of the correspondence. Such personalized correspondence receives a better response from the receiver of such mail as compared to the response obtained from a non-personalized mass mailing.
The problem which arises in sending personalized letters in personalized envelopes is to be certain that the letter and envelope match exactly with respect to the addressee and his/her address. Normally, this matching operation is done by hand using costly human labor to read each name and hand enclose. By assigning unique identifying numbers to each addressee and using this to control match, a machine operator can control accuracy.